Particularly in the self-storage industry, multiple storage units are made available and are leased to consumers requiring semi-permanent storage. Door locks at such facilities are of great importance to give both the managers of the storage facility and customers independent access and the required security. Also, it is important, particularly with outdoor access to storage areas to provide door locks, which will withstand adverse weather conditions that may lead to rust and corrosion. In an effort to avoid deterioration and corrosion, it is desirable to use corrosion and rust resistant materials such a premium grades of stainless steel. Unfortunately, such materials, although desirable for producing door latches, are non-magnetic and preclude the use of alarm and security systems using magnetic switches.
An elucidating background is set forth in U.S. Pat. No. 6,249,224. The disclosed alarm switch assembly includes a housing having first and second surfaces and an opening defined therein that extends from one surface-toward the other surface. The opening is further defined by at least four inner surfaces. A magnetic field generating device is disposed adjacent the opening and between the first and second surfaces, and a switch is disposed adjacent the opening and is opposed to the magnetic field generating device. More particularly, a magnet chamber and switch chamber are defined on opposite sides of a latch-receiving slot. When the latch is in its closed position, thus being fully inserted in latch slot, the magnetic field produced by magnet is “blocked” by the metal slidable door latch, thereby maintaining alarm switch in the “closed” position. Given that only ferrous materials can “block” a magnetic field, the latch in this and other known configurations is iron-containing, probably ferrous steel.
The point of novelty of the '224 has to do with clearances as opposed to materials. The slot is preferably dimensioned such that a slidable door latch fits therein with a relatively small amount of clearance on each side, preventing a “dummy” latch to be inserted therein. As used therein, a “dummy” latch is an object that can be inserted between slidable door latch an inner surface of the slot such that when the latch is withdrawn, the object “blocks” the magnetic field produced by magnet and prevents same from affecting alarm switch. Given that even this tamper-resistant configuration includes a latch subject to corrosion, the need remains for an improved more weather-resistant alternative.